1. Field of the Invention
The present invention relates to a hypercable antenna control (HyCAnC®) process for individual reception and collection of Lband distribution for terrestrial transmission networks, particularly for Hypercable transmission networks or satellite transmission networks.
2. Description of Related Art
Receiver/Decoders, analog or digital, used in network and/or satellite transmission networks usually have a reception range associated with normal use. Most satellite decoders have a signal range from −70 dBm to −20 dBm although some decoders may have different limitations, but the principle remains the same for all type of systems. Antennas receive RF signals for down conversion and transmission to the decoders. The antennas used in network and satellite transmissions usually have a passive device, i.e., offset-dish—array—dipoles, and an active device, which includes a mixer for down conversion and a low noise amplifier (LNA) that amplifies the signal received by the passive device. The active device may include several amplification stages that may amplify either the RF signal, IF signal, or both the RF and IF signals. Similar to decoders, the amplifiers used in the antennas are also subject to limitations and have operational ranges associated with them.
Terrestrial transmission of signals involves the transmission of signals horizontally across a terrestrial plane. Transmitters may receive RF signals from a satellite and transmit the RF signals to antennas that down convert and transmit to an end user decoder. The signal strength between the transmitter and decoder usually correlates to the distance of between the receiver/decoder and the transmitter. At relatively short distances between the receiver/decoder and transmitter, the signal strength tends to be very high, conversely as at longer distances between the receiver/decoder and transmitter signal strength tends to weaken and become very low. Consequently, the decoder's operational parameters, upper and lower limits, may well depend upon the distance between the receiver/decoder and transmitter, where if the distance is too close or too great, then the receiver/decoder will not probably receive the signal. Table A, below, shows some exemplary readings which demonstrate characteristics associated with terrestrial transmission.
TABLE AOne Carrier15 CarriersDistance fromLevel =Level = −75 dBmLevel = −60 dBmTransmitter = 2 km −90 dBmDistance fromLevel =Level = −99 dBmLevel = −84 dBmTransmitter = 32 km−120 dBm
In contrast, satellite signal transmission functions in a different manner than terrestrial transmission. The signals associated with satellite transmissions are usually uniform across a large area. The satellite signal transmissions are substantially the same for an entire continent and/or country and a receiver/decoder receiving satellite signals usually receive substantially the same signal strength wherever the receiver/decoder is located inside the satellite footprint. Table B shows exemplary readings associated with satellite transmissions.
TABLE BSatellite Reception Field Levels −150 dBw (−120 dBm):Paris =−120 dBm dist from Satellite = 36,400 kmBarcelona =−120 dBm dist from Satellite = 36,200 km
Base upon the foregoing, one can realize that the modification of terrestrial transmission may be necessary in order to ensure proper receipt by the decoders. The amplifiers within the antenna's active device may be used to address problems associated with terrestrial signal transmission. Usually these amplifiers apply a gain to the RF signal or converted IF signal in order to prevent fading that may occur. The amplifier may however inadvertently and unnecessarily amplify signals with sufficient strength for reception by the decoder. On these occasions, the amplifiers actually saturate the signal and consequently produce a signal that is too strong for reception by the decoder, such as in one exemplary embodiment a 1 GHz LNB may have an max gain of −55 dBm.
U.S. Pat. No. 6,512,428 to Hirtzlin et al. (Hirtzlin) relates to a device which affects the simultaneous reception/transmission of signals between a decoder and terrestrial base station. The Hirtzlin device employs a low-noise amplification stage in order to control parasitic coupling between the transmission and reception signals. The reception path may be disturbed by a parasitic signal created by coupling of the transmission signal transmitted over the transmission path. The parasitic signal may saturate the input stage of the reception path and the Hirtzlin device provides a means to minimize the degradation brought about by the parasitic signal.
U.S. Pat. No. 6,549,754 to Miller et al. (Miller) relates to an in-flight entertainment (IFE) system that provides live video/audio programming to passengers and operators over an aircraft video/audio distribution system. The Miller system uses programming signals from intermediate frequency (IF) signals that are produced by frequency down converting satellite broadcast signals and supplied over a pair of IF signal output cables. The Miller also uses control signals and DC power in the frequency down conversion process over the IF signal output cables in a reverse direction.
U.S. Pat. No. 6,549,755 to Chu et al. (Chu) relates to a method and apparatus for monitoring and controlling the operating point of a satellite transponder amplifier. Chu is directed toward controlling the transmission of signals from a satellite to terrestrial transponders. The Chu apparatus develops a histogram of the received signal and compares the acquired histogram to a template histogram in order to determine an amount of compression. The apparatus then uses the amount of compression to determine the operating point of the satellite transponder amplifiers.
The prior art however fails to address fading and saturation that may occur between a terrestrial antenna and an end user decoder. It would accordingly be advantageous to have a system and method to selectively amplify and control the amplification of input signals to the decoder based upon instantaneous commands from the target decoder. By using the decoder commands, the active device of the antenna may readily maintain an acceptable IF signal for receipt by the decoder while avoiding the saturation and fading problems discussed above.